Trachoma is the leading cause of blindness in the world. The causative agent, Chlamydia trachomatis, is a obligate intracellular parasite which produces nearly every known immunological response to host. It is imperative that any type of vaccine production take into account the immunopathology associated with this disease. We are convinced that immunity does exist and that immunity is directed toward the type-specific antigens present on the surface of the infected form of the microorganism. We have isolated antigens (serotypes A, B and C) from the three ocular strains of C. trachomatis. This was accomplished by isolating the type-specific antigens from the supernatants of infected cell cultures. The procedure involves ion-exchange chromatography, gel filtration and molecular shift chromatography. In addition a rapid test for serodiagnosis is being developed through the use of enzyme-immunoassay. The test system has been utilized for the detection of group as well as type-specific antigens. The proposed research will include studies on the specific antibody responses in tears and sera (IgG, IgA and IgM) to the specific antigens. The tears and sera are from infected human patients with trachoma. In addition, the specific antibody responses will be studied in the tears and sera of infected primates. Cell mediated responses to the specific antigens in the infected monkeys will be monitored. The rationale involved in this study is the fact that these primates are immune to reinfection. We hope to present the antigen to the host in a manner which will segregate those responses leading to immunity from those involved in pathogenesis.